超标准暴雨洪水条件下南水北调中线工程沿线各单元风险评估

Risk assessment of each unit along the middle route of South-to-North Water Transfer Project under over-standard rainstorm flood conditions

对南水北调中线工程沿线639个单元工程风险进行评估,并对灌渠河、贾河、金水河、石门河和沙沟5个典型单元进行重点分析。结果表明:中线工程沿线639个评估单元中,风险事件可能性指数为1的单元占比最大,风险等级以一般风险为主;在5个典型单元中,极端降雨移用(植)后在交叉断面处形成的洪水基本上呈现流域面积越小洪水量级越大的特点。此外,灌渠河排水倒虹吸发生渠顶漫溢的风险低;贾河梁式渡槽、沙沟排洪渡槽和石门河渠道倒虹吸均存在较高的工程风险;金水河渠道倒虹吸在超标准洪水下河道冲刷满足要求,工程风险较低。研究成果对提前部署南水北调中线工程防御超标准暴雨洪水具有指导意义。

The middle route of South-to-North Water Transfer Project is a large-scale water diversion project with cross-basin,large flow,and long distance.It is a major strategic infrastructure to alleviate the shortage of water resources in northern China,realize the rational allocation of water resources,and ensure sustainable economic and social development.With global warming,the frequency of extreme rainstorm and flood disasters has increased significantly.Since its operation,the middle route of South-to-North Water Transfer Project has encountered severe torrential rainstorm disasters many times,and is facing serious problems of water damage.Therefore,it is necessary to further study the degree of risk in the middle route project when encountering over-standard rainstorms floods.The channels and buildings of the middle route of South-to-North Water Transfer Project were taken as the research object,and the method of combining the overall risk assessment and the typical unit analysis was used to evaluate the overall risk of 639 units of the middle route project,and the five typical units of Guanqu River,Jia River,Jinshui River,Shimen River,and Shagou were focuses on.In engineering risk analysis,methods such as engineering risk event possibility index and engineering risk event consequence severity were adopted.In the risk analysis of over-standard rainstorms floods,the risk of typical assessment units was analyzed through the construction of rainstorms flood analysis model,extreme rainfall migration(planting)setting,scheme simulation,and statistical analysis of results.The results show that among the 639 evaluation units of the middle route of South-to-North Water Transfer Project,the units with a risk event probability index of 1 account for the largest proportion,and the risk level is mainly general risk.In the five typical units,the flood formed at the cross-section after extreme rainfall migration(planting)presents the characteristics that the smaller the watershed area,the larger the flood magnitude.In addition,the risk of overflow at the top of the irrigation canal river drainage inverted siphon is low.The Jiahe beam aqueduct,Shagou flood discharge aqueduct,and Shimen River channel inverted siphon all have high engineering risks.The erosion of Jinshui River channel inverted siphon meets the requirements under over-standard flood,and the project risk is low.The conclusion indicates that under the condition of over-standard rainstorm flood,the channels and buildings of the middle route of South-to-North Water Transfer Project are generally low-risk,but some typical units have engineering risks such as insufficient flood control capacity,overflow of trough body,and embankment top,erosion and exposure of piers and abutments,and dam failure.Therefore,to ensure the safe operation of the middle route project,it is still necessary to further strengthen the engineering and non-engineering protection measures,and scientifically and reasonably formulate the revision mechanism of the over-standard rainstorm flood prevention plan.The research results have guiding significance for the early deployment of defense against the over-standard rainstorm flood in the middle route of South-to-North Water Transfer Project.